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|저자명||Hoon Huh Kwanghyun Ahn Hyung Won Kim Lee Ju Park Ji Ho Lim|
This paper evaluates existing well- known dynamic hardening models for metallic materials of typical crystalline structures. The information of the dynamic response of metallic materials is indispensable for the analysis of deformation and loading states under high strain rate conditions. Although various dynamic hardening models have been suggested by many researchers, a unique model is hardly found to represent the dynamic hardening characteristics of all types of materials. In order to evaluate existing dynamic hardening equations reported, materials for three typical crystalline structures have been selected and evaluated using the dynamic hardening characteristics of three kinds of materials: 4340Steel (BCC); OFHC (FCC); and Ti6Al4V (HCP). The dynamic hardening characteristics of each material have been obtained from uni-axial tensile tests and Split Hopkinson Pressure Bar tests. Uni-axial quasi-static and dynamic tensile tests have been performed with the variation of the strain rate from 0.001/sec to 100/sec, and SHPB tests have been conducted at higher strain rates ranging up to 4000/sec. Several existing models have been constructed and evaluated for the Johnson-Cook model, the Zerilli-Armstrong model, and the Preston-Tonks-Wallace model with the test results of the three materials. Several models suggested by the authors have also been compared for the modified Johnson-Cook model, the modified Khan-Huang model, and the Lim-Huh model. The change of the strain rate and the temperature during the deformation process was taken into account for the accurate applications of the hardening equations. The most applicable equation for each material has been recommended after thorough comparison of the constructed results.